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Analysis of Coding Gain Due to In-Loop Reshaping

delete2024-01-01
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PRE
AI
C
Chau-Wai Wong
C
Chang–Hong Fu *
M
Mengting Xu
G
Guan‐Ming Su
DOI:10.1109/TIP.2024.3409189delete
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Abstract

Abstract

En 中文
Reshaping, a point operation that alters the characteristics of signals, has been shown capable of improving the compression ratio in video coding practices. Out-of-loop reshaping that directly modifies the input video signal was first adopted as the supplemental enhancement information (SEI) for the HEVC/H.265 without the need to alter the core design of the video codec. VVC/H.266 further improves the coding efficiency by adopting in-loop reshaping that modifies the residual signal being processed in the hybrid coding loop. In this paper, we theoretically analyze the rate-distortion performance of the in-loop reshaping and use experiments to verify the theoretical result. We prove that the in-loop reshaping can improve coding efficiency when the entropy coder adopted in the coding pipeline is suboptimal, which is in line with the practical scenarios that video codecs operate in. We derive the PSNR gain in a closed form and show that the theoretically predicted gain is consistent with that measured from experiments using standard testing video sequences.
Keywords:
Videos
Image coding
Standards
Quantization (signal)
Video coding
Video codecs
Transforms
In-loop reshaping
out-of-loop reshaping
quantization
video compression
VVC/H.266

Journal

IEEE Transactions on Image Processing cover
IEEE Transactions on Image Processing
IF:
13.7
Papers:
1.0W
Citations:
8.4W

Organization

D
dolby laboratories, inc.
Scholars:
51
Papers: 22
Citations: 0
N
North Carolina State University
Scholars:
2.6W
Papers: 2.3W
Citations: 3.7W